There are many online services that offer users to connect to other users and share information including media such as photos and videos. These services are commonly referred to as social network services. Several social network services (e.g., FACEBOOK®, FLICKR®, and GOOGLE+®) and third-party web services (e.g., FACE.COM®'s FACEBOOK® application) provide semi-automated user interfaces for users to apply a tag or annotation to a face in an image and link the face with a corresponding user's account. For example, a tag or annotation is a location marker that denotes a landmark in an image. A user face tag may be a rectangle or a point on the image that denotes the location of a person's face. Systems and processes that provide automated face tagging or annotation using face recognition have been described in U.S. Pat. Pub. No. US2010/0063961 by Guiheneuf, et al. (hereinafter “Guiheneuf”) entitled “Reverse Tagging of Images in System for Managing and Sharing Digital Images”.
Automatic facial recognition is a particular application in the field of computer vision and image processing. It involves comparing two faces and generating a match or similarity score (or distance score) that is a measure of how similar the two faces are to each other. A threshold based on the similarity score is used to classify whether the two faces belong to the same person, or two different people. The process of face recognition involves extraction of one or more types of low-level image features, deriving one or more high level representations of the two faces based on pre-trained models, and comparing the high level representations of the two faces to each other to derive the distance or similarity between them using some metric. A survey of face recognition methods has been described by Zhao, et al. (Zhao et al., “Face Recognition: A Literature Survey”, ACM Comput. Surv. 35, pp. 399-458, Dec. 4, 2003) (hereinafter “Zhao”).
While several software and social network services currently offer tools that use face recognition for automated suggestions for tagging faces in images, these tags and tools are optional. If tags are not added to these images, the faces of corresponding users are not easily found again. Moreover, tags are only offered to the creator who create or uploads a photo, photo album or video, and not to the user whose face is contained within the photo. Therefore, users are reliant on their friends or connections to inform them of these uploaded photos directly or by applying the annotation tool. When the creator uses the annotation tool to tag the face in an image to a second user, the social network service notifies the second user of the new image posted. If the tag is not added to the image by the creator, the second user may be unaware of this new image of them online. This is a major concern for many users of social network services, as they are not in control of their online image footprint, and may be unaware of their related information being shared with the world.